Transceivers are used frequently within communications equipment to transfer information, generally through the conversion of electrical impulses to light impulses and vice-versa. Lasers and photodetectors permit such conversions within transceivers. Unfortunately, the distance such information can be transported is limited by the output optical power of the laser, the non-linearity effects of fiber (dispersions), and other limitations of the receiver.
As the optical communications network employs such a transceiver (or a plurality of transceivers) as a mechanism for data transfer, it is important that the laser output present no health hazard to bystanders. For example, if the optical cable were to become unplugged, the laser output would no longer be contained and may be freely emitted into the environment. It is possible that the emitted laser output may be received by a human eye, and if the intensity of the laser output is too high, harm could occur. Accordingly, for safety purposes, the optical intensity of the laser is kept low such that eye safety is assured should the optical cable become unplugged. Conventional optical transceivers thus have eye safety mechanisms, such as laser bias monitors, for example, that shut down the optical transceiver should the optical power become too large.
Typically, then, past configurations of such optical transceivers were subject to electrically controlled eye safety implementations (such as through the utilization of either hardware or firmware) and all possible single point failure conditions that can cause unsafe levels of laser power were initially identified. It was imperative that, if a single point of failure existed, any such eye safety protocols demonstrate compensation for any such single point failure by either turning the laser off or by limiting the laser optical output power. More important, however, was to avoid any devices that exhibited potential single-point failures. Even in such situations, it was necessary to provide effective protections from eye injuries were the laser portion to become compromised, regardless of the number of failures points present.
It is thus a requirement that such optical transceivers be eye-safety compliant, particularly in the case of not having a single point failure within the transceiver itself. Currently, however, the best methods of controlling any such single- or multiple-point problems also require lower laser power levels to be initially utilized; nothing has been provided within the optical transceiver industry that allows for instantaneous shut-off upon of a laser upon exposure of the laser diode itself to an area outside the transceiver module. Double fault conditions are now primarily utilized and generally followed to prevent any single failure point. With such a double-point failure protocol, at least it has become easier to prevent the subject laser power from reaching unsafe open bore levels upon decoupling from the transmitter port.
This eye-safety problem basically concerns the possibility that the subject laser cannot be deactivated quickly during a fault condition, a system failure, laser or transceiver replacement, or other like activity. To combat such a potential occurrence, the usual reply within the industry has been, as noted above, to decrease laser strength (to lessen the potential eye damage) or to include an entire shut off of the processor in response to changes in the integrity of the system itself, as well as the possibilities mentioned above about optical intensity thresholds. Such remedies have proven uneven at best; reducing initial laser strength in turn decreases transmission distance and hence makes optical networks more complex and costly. Thus, it has been an aim within this industry to provide a manner of increasing laser strength while best ensuring that eye safety is itself not compromised with such an increase in laser strength.
Furthermore, the best remedy for such a problem should take into account the necessity of a separate, independent capability of controlling the power relayed to the subject laser during any type of failure. The previous protocols have not implemented any such possible method or manner. As such, to date, the communications industry has been limited in laser power utilization in order to provide effective and reliable eye-safety mechanisms for potential system breaches or failures. No acceptable previous developments have been accorded the industry to aid in this deficiency.